1. Field of the Invention
The present invention relates to an evaporation apparatus for evaporating an evaporation material sublimated from an evaporation source to an evaporation object, a method of manufacturing an anode using the same, and a method of manufacturing a battery using the same.
2. Description of the Related Art
In recent years, high performance and multifunction of mobile devices have been developed. Accordingly, for secondary batteries as a power source for the mobile devices, it is demanded to achieve their high capacity. Lithium ion secondary batteries satisfy such a demand. Recently, the lithium ion secondary batteries having an extremely high capacity have been developed by using silicon (Si) and tin (Sn) as an anode active material.
However, in the anode active material using silicon, tin and the like, the expansion and shrinkage due to charge and discharge are significant. Thus, it is often the case that the lowering of the cycle characteristics due to pulverization becomes an issue. Thus, the applicants of the invention have proposed the following technique. In the technique, the anode active material is formed by using vapor-phase deposition method or the like. Thereby, the pulverization is inhibited, and the current collector and the active material layer are unified to obtain extremely favorable electron conductivity in the anode (for example, refer to Japanese Unexamined Patent Application Publication No. 2004-349162). In such an anode and a battery including such an anode, high performance is expected for both the capacity and the cycle life.
As the vapor-phase deposition method, for example, Physical Vapor Deposition (PVD) method such as vacuum evaporation method in which a target (evaporation source) is heated, volatilized, and evaporated; sputtering method in which inert gas is turned into plasma by glow discharge or high frequency, and thereby a target is in a state of sputtering; and ion plating method in which a substrate is in a state of high potential, and an ionized target is deposited on the substrate is known. In addition, Chemical Vapor Deposition (CVD) method is also known. Of the foregoing, in the sputtering method, though the film thickness is able to be delicately adjusted, the deposition rate is slow and thus there is an issue in mass production. In the ion plating method, there is an issue that since the temperature of the substrate as the evaporation object is increased, and thus the substrate material is limited. In the CVD method, it is more disadvantageous than the foregoing PVD method in terms of mass production. Accordingly, when the anode active material is formed on the anode current collector, the vacuum evaporation method is suitable. In the method, relatively high production efficiency is obtainable and high quality is easily ensured. In general, in the vacuum evaporation method, the following procedure is made. That is, an evaporation material is physically heated and melted by an electron beam and a resistive element, part thereof is sublimated and deposited on the surface of the evaporation target. Thereby, a thin film made of a desired material is formed.